Material for bearing retainer

Abstract

There is provided a porous material suitable for use in a bearing retainer, having such properties as a small contraction ratio of the dimensions of a formed workpiece to those of a finished product, excellent hot oil resistance, small contraction change, insusceptibility to damage, light weight, a long service life, and ability to retain oil and grease for a long period of time. The porous material suitable for use in the bearing retainer is obtained by a process comprising the steps of mixing degreased bran derived from rice bran with a thermosetting resin before kneading, subjecting a kneaded mixture to a primary firing in an inert gas at a temperature in a range of 700 to 1000° C., pulverizing the kneaded mixture after fired into carbonized powders sieved through a 60-mesh screen, mixing the carbonized powders with a thermosetting resin before kneading, pressure-forming a kneaded mixture thus obtained at a pressure in a range of 20 to 30 MPa, and applying a heat treatment again to a formed kneaded mixture in the inert gas at a temperature in a range of 100 to 1100° C.

What is claimed is:  
     
       1. A porous material suitable for use in a bearing retainer, obtained by a process comprising the steps of mixing degreased bran derived from rice bran with a thermosetting resin before kneading, subjecting a kneaded mixture to a primary firing in an inert gas at a temperature in a range of 700 to 1000° C., pulverizing the kneaded mixture obtained after the primary firing into carbonized powders sieved through a 60-mesh screen, mixing the carbonized powders with a thermosetting resin before kneading, pressure-forming a kneaded mixture thus obtained at a pressure in a range of 20 to 30 MPa, and applying a heat treatment again to a formed kneaded mixture in the inert gas at a temperature in a range of 100 to 1100° C. 
     
     
       2. A porous material suitable for use in a bearing retainer according to  claim 1 , wherein the thermosetting resin is one kind or not less than two kinds selected from the group consisting of a phenol resin, diaryl phthalate resin, unsaturated polyester resin, epoxy resin, polyimide resin, and triazine resin. 
     
     
       3. A porous material suitable for use in a bearing retainer according to  claim 1 , wherein a mixing ratio of the degreased bran to the thermosetting resin is 50˜90:50˜10 by weight. 
     
     
       4. A porous material suitable for use in a bearing retainer as set forth in  claim 1 , wherein a mixing ratio of the carbonized powders to the thermosetting resin is 50˜90:50˜10 by weight. 
     
     
       5. A porous material suitable for use in a bearing retainer as set forth in  claim 1 , wherein a particle size of the carbonized powders is in a range of 50 to 250 μm. 
     
     
       6. A porous material suitable for use in a bearing retainer as set forth in  claim 1 , wherein the thermosetting resin mixed with the degreased bran is in a liquid state, and the thermosetting resin mixed with the carbonized powders is in a solid state.